1. Field of Invention
This invention relates to systems on cars, trucks, buses, ambulances, and trains that reduce the collision damage on the vehicle, its occupants, and collidants.
2. Description of Prior Art
Most vehicles and structures have some exterior system to deal with collisions. Automobiles have the five mile per hour bumpers with metal hydraulic shock absorbers or polymer foams. Trucks have rigid metal bumpers that might crumple during a collision. Trains used to have cow catchers.
Disadvantages
The five mile per hour bumper is relatively useless at preventing property damage and personal injury at speeds above 5 mph. U.S. Pat. No. 4,869,538 addressed this problem by putting a rubber inner tube around the outside of the front bumper. This tube was permanently inflated. It had to be rather small to deal with the limits of parking spaces. It never became commercial because of wind drag, aesthetics, weight, expense, and the impression that one was driving a stolen car from a carnival bumper car ride. This air filled bumper did reduce collision forces and added a few miles per hour to the lower threshold for vehicle damage. The tube is much too small to keep collidants under the 18 g level that causes bodily injury, at speeds above 10 mph.
U.S. Pat. No. 3,656,791 has an inflatable exterior air bag actuated by a probe inside the air bag cover. But this bag inflates after the impact begins to damage the vehicle and the collidant. This bag reduces damage only at speeds less than 10 miles per hour. This small bag, only about 4 cubic feet, also increases the forces on the vehicle and collidant by creating more recoil after collision contact.
Trains used to have cow catchers. But today trains go so fast that they will kill anything they hit, cow catcher or not. Therefore, they have no collision damage reduction systems other than a manual brake, horn, and lights.
Trucks have heavy steel bumpers with no force reduction systems. They too kill anything they hit because of their 100,000 pound plus mass and high speeds. Their only collision damage reduction systems are manual lights, brakes, steering, and horns. A few trucks have collision warning radars and sonars, but these systems only turn on lights and beepers inside the cab to alert the driver. Some actuate brakes or throttle. These radars are very expensive with many years to payback.
Some buses have water filled bladder bumpers that reduce collision forces. These systems are too small to do more than shave 5 mph off a collision's severity. Otherwise, buses are limited to the collision damage reduction systems listed for trucks.